affter add the 3 piece into caffe file, when make caffe, crt1.o error happen, how to solve it?

[PiseyYou]

when I make cope the depthConv_layer to the caffe root, when I make caffe, always the crt1.o happen, the key error is display as below:
/usr/lib/gcc/x86_64-linux-gnu/5/../../../x86_64-linux-gnu/crt1.o: In function _start': (.text+0x20): undefined reference to main'
collect2: error: ld returned 1 exit status

any suggetion how to solve it?